This invention relates to apparatus for refining glass. The principal objective of melting and refining glass is to produce a molten glass that is useful for the intended purposes. Among the criteria utilized to determine the quality of the molten glass are the absence of seeds or bubbles caused by entrapped gas and insufficiently melted materials. The intended use of the glass determines the extent to which seeds can be retained in the glass. Such seeds are a necessary result of the chemical reactions that occur during the melting of the glass-forming materials. Seeds are also described in the art as gaseous inclusions. Large seeds are designated blisters; however, there is no sharp line or demarcation between the classification of seeds and blisters. Seeds generally fall into the size range of 0.0001 inch to 0.030 inch in diameter. This apparatus removes gaseous inclusions most effectively when the seeds are in the range of about 0.001 inch to 0.030 inch and upwards in diameter. However, the operating parameters may be varied to remove seeds of a smaller size, such as increasing the residence time of the molten glass.
In making glass by conventional methods in commercial quantity, the glass-forming materials are usually introduced into a melter which comprises a large volumetric area and are subjected to large quantities of heat. The glass is maintained in the melting area for long periods of time and small quantities are continuously removed as they become molten. The glass is then further subjected to controlled heat in a large volumetric mass to further melt the components that may be interspersed therein and remove gases, and finally the glass is moved slowly to a third volumetric area known as a conditioning zone. Such prior art methods and apparatus involve very large tanks and large quantities of heat in order to produce the desired output.
In the copending application of Richards et al, Ser. No. 130,672, filed Apr. 2, 1971, titled "Method and Apparatus for Refining Molten Glass", now U.S. Pat. No. 3,754,886, having a common assignee with the present application, there is disclosed and claimed a method and apparatus for refining molten glass which has undesirable gaseous inclusions.
The method disclosed in the aforementioned application for removing undesirable gaseous inclusions, also known as seeds and bubbles, from seed containing or unrefined molten glass comprises continuously introducing this unrefined molten glass into a rapidly rotating contained glass mass, subjecting the unrefined molten glass mass to centrifugal forces substantially greater than gravity, and developing static pressure differences in the glass mass, resulting in pressure gradients in the molten glass that cause the gaseous inclusions to migrate to areas of lower static pressure and to the atmosphere from the molten glass, delivering refined molten glass from the contained glass mass having reduced numbers of gaseous inclusions.
Among the objects of the present invention are to provide an improved apparatus for refining glass which utilizes the method of the aforementioned application; which apparatus will function effectively and be maintained readily with long life; which apparatus includes means for controlling the temperature thereof; which apparatus further includes means for lubricating and cooling the apparatus as well as the bearings utilized therein.